Pro Ace pedal threading?

Hi all,
Was wondering if anyone knew if Kyokuto Pro Ace pedals from the 1970s were
available in French threading?
I have a Peugeot from that vintage, and can't remember re-threading the
cranks, but it has those pedals. Am considering upgrading to SPD compatible
pedals, but am not sure I want to make the bike less than original by
changing the threads. Unless I already have, that is.
Or, any suggestions on how I can determine if the current threads in the
crank are French or 9/16 x 20?
Thanks for any help, and Merry Christmas,
Kerry

Kerry Montgomery wrote:
Hi all,
Was wondering if anyone knew if Kyokuto Pro Ace pedals from the 1970s were
available in French threading?
I have a Peugeot from that vintage, and can't remember re-threading the
cranks, but it has those pedals. Am considering upgrading to SPD compatible
pedals, but am not sure I want to make the bike less than original by
changing the threads. Unless I already have, that is.
Or, any suggestions on how I can determine if the current threads in the
crank are French or 9/16 x 20?
Thanks for any help, and Merry Christmas,
Kerry

Look on the pedal spindle near the crank.
BSC pedals are marked R + L or less likely 9/16"-20
Metric pedals are marked D + G or less likely m14x1.25

It's good practice to change or strike the mark on the
inside of the crank itself from 14mm to 9/16" after tapping,
just as engine cylinders should be stamped +010 or +020 for
overbores. That may or may not have been done if they were
perhaps tapped to BSC.

The difference is very slight (.0117 inches) so there's no
particular mechanical reason not to tap to the larger
current size.

In case anyone's curious, Italian 9/16" equipment is D + S,
Spanish 14mm are D + I.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

On 12/24/2010 1:47 PM, Kerry Montgomery wrote:
Hi all,
Was wondering if anyone knew if Kyokuto Pro Ace pedals from the 1970s were
available in French threading?
I have a Peugeot from that vintage, and can't remember re-threading the
cranks, but it has those pedals. Am considering upgrading to SPD compatible
pedals, but am not sure I want to make the bike less than original by
changing the threads. Unless I already have, that is.
Or, any suggestions on how I can determine if the current threads in the
crank are French or 9/16 x 20?

My Pro-Ace pedals aren't marked with thread dimensions on the axle, but
I expect you knew that.

My ancient Palo Alto bike shop catalog (1976) wasn't any help, sorry.
It carried Pro-Ace's, but had /no/ French thread pedals in any model,
which is hardly conclusive.

I'd bet that the KKT's /did/ come in french thread, but that still
doesn't answer your question.

So: If you can get your hands on any pedal from a modern quality bike
(not one-piece cranked department store special), see if it will thread
into your Peugeot's crank. If not, the crank's french-threaded. If so,
the crank's 9/16 x 20.

Finally, a 9/16 x 20 thread's outer diameter is about 14.2 mm (measured
just now), the outside diameter of a french thread pedal axle will be a
bit less (as little as 0.2 mm less). See Sheldon's table:
http://www.sheldonbrown.com/gloss_p.html#pedal
(I recommend reading this link).

Good luck,

Mark J.

On Dec 24, 10:43*pm, AMuzi wrote:
Kerry Montgomery wrote:
Hi all,
Was wondering if anyone knew if Kyokuto Pro Ace pedals from the 1970s were
available in French threading?
I have a Peugeot from that vintage, and can't remember re-threading the
cranks, but it has those pedals. Am considering upgrading to SPD compatible
pedals, but am not sure I want to make the bike less than original by
changing the threads. Unless I already have, that is.
Or, any suggestions on how I can determine if the current threads in the
crank are French or 9/16 x 20?
Thanks for any help, and Merry Christmas,
Kerry

Look on the pedal spindle near the crank.
BSC pedals are marked R + L or less likely 9/16"-20
Metric pedals are marked D + G or less likely m14x1.25

Not to be assumed generally, my BSC Time pedals are marked with both
sets of letters. They are also marked ... 9/16 x 20 IIRC (too much
of an effort to check, they're buried right now).

It's good practice to change or strike the mark on the
inside of the crank itself from 14mm to 9/16" after tapping,
just as engine cylinders should be stamped +010 or +020 for
overbores. That may or may not have been done if they were
perhaps tapped to BSC.

The difference is very slight (.0117 inches) so there's no
particular mechanical reason not to tap to the larger
current size.

In case anyone's curious, Italian 9/16" equipment is D + S,
Spanish 14mm are D + I.

--
Andrew Muzi
* www.yellowjersey.org/
* Open every day since 1 April, 1971

"Mark J." wrote in message
...
On 12/24/2010 1:47 PM, Kerry Montgomery wrote:
Hi all,
Was wondering if anyone knew if Kyokuto Pro Ace pedals from the 1970s
were
available in French threading?
I have a Peugeot from that vintage, and can't remember re-threading the
cranks, but it has those pedals. Am considering upgrading to SPD
compatible
pedals, but am not sure I want to make the bike less than original by
changing the threads. Unless I already have, that is.
Or, any suggestions on how I can determine if the current threads in the
crank are French or 9/16 x 20?

My Pro-Ace pedals aren't marked with thread dimensions on the axle, but I
expect you knew that.

My ancient Palo Alto bike shop catalog (1976) wasn't any help, sorry. It
carried Pro-Ace's, but had /no/ French thread pedals in any model, which
is hardly conclusive.

I'd bet that the KKT's /did/ come in french thread, but that still doesn't
answer your question.

So: If you can get your hands on any pedal from a modern quality bike (not
one-piece cranked department store special), see if it will thread into
your Peugeot's crank. If not, the crank's french-threaded. If so, the
crank's 9/16 x 20.

Finally, a 9/16 x 20 thread's outer diameter is about 14.2 mm (measured
just now), the outside diameter of a french thread pedal axle will be a
bit less (as little as 0.2 mm less). See Sheldon's table:
http://www.sheldonbrown.com/gloss_p.html#pedal
(I recommend reading this link).

Good luck,

Mark J.

Andrew and Mark,
Thanks much. The pedals are marked L and R, and the outside diameter is
14.17 mm, so modern pedals should thread right in. The pedals also have a
102 marked on them, whatever that might mean. I'll mark the inside of the
crank 9/16, too.
Thanks again,
Kerry